<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<script>
    var n = new Number(10);//可像纯数字一样参于运算
    console.log(typeof n);  //object
    console.log(n instanceof Number); //true

    var m = 20;
    console.log(n/m);
    var x = 12.333;
    console.log(x.toFixed(2));

</script>
</body>
</html>